Procedure for generating fluoroscopic images for reconstituting volume in flat object by using x-ray system

Abstract

To provide a procedure for generating fluoroscopic images for reconstituting a volume in a flat object by using an X-ray system.SOLUTION: A procedure for generating fluoroscopic images for reconstruction of a volume in a flat object using an X-ray system, which has: a tube 1; a detector 3; and a manipulator, with an object 2 being fixed between the tube and the detector. Therein: a vector from the tube through a volume 5 forms an x axis of a coordinate system; the manipulator is rotated about a rotational axis 4, which is perpendicular to the x axis, and is displaceable parallel to the x axis; a distance between the tube and the rotational axis is altered such that when the flat object is rotated about the rotational axis, a distance between the object and the tube at every angle of rotation (Θ) becomes as small as possible without falling below a definable minimum distance; fluoroscopic images are made at pre-definable angles of rotation (Θ) and angle increments between neighbouring pre-definable angles of rotation (Θ) are larger in the case of smaller distances from the tube to the rotational axis than in the case of larger distances from the tube to the rotational axis.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for generating perspective images for reconstructing the spatial extent (Volumen) of a flat object using an X-ray system having a tube, a detector and an object located between them. [Background technology]

[0002] The field of use of the invention is X-ray based material testing. Industrial actors such as the automotive industry or electronics manufacturers use X-ray systems in the context of X-ray based material testing to test the properties of objects, in particular their components. Here, the use of X-rays for imaging allows the investigation of hidden structures without destroying the object.

[0003] The test is carried out in an X-ray system having as imaging system an X-ray tube (hereinafter also called tube) and an X-ray detector (hereinafter also called detector). The object to be examined is placed between them on a manipulator. Some or all of these three abovementioned components can be moved in a translational and / or rotational manner depending on the X-ray system. The whole apparatus is located in a radiation protection cabin (hereinafter also called cabin). Since the geometry of the images taken with this X-ray system depends on the focal point of the tube, in the following the tube will also be simply called the focal point.

[0004] In non-destructive testing of large flat components (e.g. printed circuit boards), very high magnifications and resolutions can be achieved in 2D images. However, since this is only a projection of the entire object, all structures contained in the object are superimposed in the recorded image, and no conclusions can be made about the position of the individual components in terms of depth. With conventional computer tomography, in which the object is observed from many different angles distributed over 360°, additional depth information can be obtained. The three-dimensional object is then reconstructed from these images, and the position of all components in space is then determined. However, since the object has to rotate once during this recording without colliding with the components of the system, it is not possible to achieve a high magnification M as in 2D testing, which is determined by the focal point to detector distance (FDD) and the focal point to object distance (FOD) (M=FDD / FOD). Thus, while in the case of 2D inspection the thickness of the object has a decisive influence on the achievable resolution, in the case of CT images the width of the object above all has a limiting effect.

[0005] In the context of this application, an object refers to an article that extends many times greater in two dimensions (surface area, including width in one direction) than in its third dimension (called thickness above, referred to in this application as depth).

[0006] In order to allow a better magnification of the object (in principle only information from a particular region of interest (ROI=region of interest), referred to in the context of the present application as spatial extent) compared to conventional CT, the following laminography procedures are known from the prior art:

[0007] In rotational laminography, a flat object is rotated one complete revolution around an axis perpendicular to the object's surface and tilted (either by actually tilting the axis of rotation or by tilting the detector) with respect to the optical axis. This allows a smaller FOD and therefore a higher magnification compared to conventional CT. However, the resulting data set is not complete and artifacts (so-called Hutchen cones) appear in the reconstructed spatial extent, which reduces the resolution in depth more than in lateral direction. The larger the laminography angle, the better the depth resolution. Compared to conventional CT, fewer projections (images) are needed for good sampling, which allows a higher throughput with a lower dose.

[0008] Further laminography procedures include circular / elliptical laminography, translational laminography, swing laminography and linear laminography.

[0009] Likewise, it is known from the prior art to carry out CT procedures with variable magnification to test composite materials. In this case, at the illumination angles where the collision between the tube and the object occurs, it is possible to compensate for the magnification, which is too low in the case of conventional CT, by increasing the FOD at the expense of the magnification to such an extent that the collision can be avoided. During the scan, different magnifications occur depending on the projections, which must be taken into account when reconstructing the spatial extent from these projections. In contrast to laminography, in this case the entire Fourier space is sampled, as a result of which the typical small pyramid artifacts can be suppressed. In this case, the change in FOD occurs along a sinusoid defined by the maximum measurement of the object, the projections being recorded at regular angular increments.

[0010] The aim of the invention is to provide a procedure which allows achieving a high resolution comparable to 2D examination, while at the same time obtaining information about the position of individual components of an object in terms of depth, comparable to conventional CT, and which furthermore offers an improved throughput and a reduced dose burden compared to conventional CT.

[0011] The object according to the invention is achieved by a procedure having the features of both claims 1 and 4. Advantageous designs are specified in the dependent claims, in particular the object being an electronic component, e.g. a printed circuit board.

[0012] According to claim 1, this object is achieved by a combination of features including, inter alia, that when the object rotates around the rotation axis, the distance between the tube and the rotation axis is changed so that the distance between the object and the tube is as small as possible without falling below a minimum distance definable at the respective rotation angle. This corresponds to the above-mentioned method with variable magnification known from the prior art for testing composite materials. This results in an increased magnification compared to conventional CT. The further feature that the fluoroscopic images are made at predefinable rotation angles and that the angular increment (dr°) between adjacent predefinable rotation angles is larger for small tube to rotation axis distances than for large tube to rotation axis distances, reduces the number of fluoroscopic images compared to the variable magnification method and thereby the time required to record the reconstruction of the spatial extent. This increases the throughput while at the same time reducing the dose burden on the object and, as a result, the risk of damage to the object. The quality of the reconstruction of the spatial extent is not significantly reduced by the aforementioned distribution of angular increments compared to a complete sampling. The geometry and the movement possibilities of the individual imaging components in the X-ray system correspond to conventional CT. The spatial extent is positioned on the axis of rotation as each perspective image is produced.

[0013] An alternative solution to the problem according to claim 4 is essentially the inverse kinematics of claim 1. Instead of moving the object using a manipulator while the tube and the detector are fixed, the imaging system constituted by the tube and the detector is moved together with the fixed object. The position and orientation of the tube relative to the detector remains unchanged. The imaging system is rotated about an axis of rotation that runs perpendicular to the x-axis (formed by a vector that passes from the focal point of the tube through the spatial extent to be examined) and parallel to the z-axis (vector formed through the thickness of the object). Thus, the imaging system can be displaced parallel to the x-axis. Similar to the axis of rotation in the first alternative solution, the axis of rotation runs through the spatial extent each time a fluoroscopic image is generated.

[0014] In a first alternative solution, a further advantageous development of the invention provides that the object is fixed on the manipulator before the procedure starts, such that the resulting effective rotation axis lies within said spatial extent. The procedure according to the invention can therefore be carried out with a very simple trajectory of the manipulator, which only needs to translate along the x-axis and rotate around its rotation axis.

[0015] Another advantageous development of the invention provides that the spatial extent is positioned at each angular increment, such that a movement of the manipulator along the x-axis and / or the y-axis always places the spatial extent in the same place. As a result, the manipulator has to move on a complex trajectory and to achieve an effect similar to that of the above embodiment, it has to perform a translational movement along the x-axis and parallel to the y-axis, and a rotational movement around its rotation axis. This corresponds to a movement of the object around a virtual rotation axis.

[0016] On the other hand, the second alternative solution benefits from only one operation described in the previous paragraph, where the spatial extent is positioned at each angular increment such that a movement of the imaging system along the x-axis results in an axis of effective rotation within the spatial extent, specifically at its centre, which corresponds to a movement of the imaging system around a virtual axis of rotation.

[0017] An advantageous development of the second alternative solution provides that the tube and the detector are fixed on a frame that is rotatable about an axis oriented parallel to the z-axis and displaceable along the x-axis. Comparable structures are known from medical technology, where the imaging system in a CT procedure is usually mounted on a gantry.

[0018] The advantageous developments of the invention presented below relate to both alternative solutions.

[0019] An advantageous development of the invention provides that the central ray of the X-rays is located on the x-axis and impinges perpendicularly on the detector in the central position, so that the spatial extent of the examination object can be optimally illuminated without information being lost due to the detector surface area being small relative to the central ray.

[0020] An advantageous development of the invention, which is an alternative to the development mentioned in the previous paragraph, provides that the x-axis does not impinge on the center of the detector. This allows so-called half-beam scanning to also be performed, in which case the spatial extent is imaged approximately at the edge of the detector, so that the axis of rotation or the axis of rotation is located approximately on the marginal radiation of the X-rays. Furthermore, with a predefined magnification, the largest possible ROI can be reconstructed.

[0021] A further advantageous development of the invention provides that the ratio between the maximum and minimum angular increments corresponds to the ratio of the object's width to its depth, in particular to the ratio of the object's long side to its short side, if the object has a substantially rectangular surface area. The angular increments that an experienced person in the art sets for the periodic scan, i.e. a complete rotation of the object, can be used as a criterion for the minimum angular increment.

[0022] A further advantageous development of the invention provides that the angle increment is changed with respect to the distance of the axis of rotation or the axis of rotation from the tube. The angle increment is then preferably changed inversely proportional to the distance from the axis of rotation or the axis of rotation to the tube. The relationship between the angle increment and the distance can be selected, for example, linear or exponential. It is also possible to distribute the angle increment via a cosine function along the long and short sides of the user-defined object. The effective axis of rotation is preferably in the center of the spatial extent. As a result, the best possible illumination of the spatial extent is achieved so that the reconstruction of the spatial extent has the highest possible quality.

[0023] A further advantageous development of the invention provides that the distance between the object and the tube for each angular increment is 0.1-20 mm, preferably 1 mm. This ensures that the object has a small "safety distance" from the tube, which is not damaged by the object when rotating. At the same time, the "safety distance" is so small that the magnification is not significantly reduced compared to the maximum possible magnification (corresponding to a distance of 0 mm).

[0024] A further advantageous development of the invention provides that a predefinable minimum distance between the tube and the axis of rotation / axis of rotation is not exceeded, which can ensure that the spatial extent is completely imaged over the entire scan, even in the case of the theoretically highest possible magnification, when the distance between the tube and the object is as small as possible so that the detector is not sufficient to capture the entire spatial extent. This minimum distance is therefore predefined in such a way that the perspective image of the spatial extent of the detector is completely located on the detector, even in the case of the smallest possible distance between the tube and the spatial extent.

[0025] A further advantageous development of the invention provides that the minimum distance is selected to be at least large enough so that the spatial extent is always completely illuminated, thereby ensuring that the entire spatial extent is imaged in each projection and that for each illumination angle image data is generated for each of the spatial extent elements (also called voxels) so that the entire spatial extent is sampled as completely as possible.

[0026] A further advantageous development of the invention provides that the selection of the minimum and / or shortest distance is determined before the rotation begins, whereby the spatial extent imaged at least at the minimum / shortest distance is completely imaged across all projections. [Brief description of the drawings]

[0027] Further details and advantages of the invention are explained in more detail below with reference to examples of embodiments represented in the drawings. [Figure 1] 1 is a schematic diagram of an embodiment of the present invention, in which the orientation of imaging components for certain equidistant rotation angles is shown; [Diagram 2] Illustrative diagram of why the angle increments are different. [Diagram 3] Illustrative diagram of why the angle increments are different. [Figure 4] Illustrative diagram of why the angle increments are different. [Diagram 5]Comparison of FOD as a function of the rotation angle in the case of the known CT with variable magnification and the procedure according to the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] 1 shows a schematic representation of an X-ray system in which an object 2 to be examined is represented in six different positions according to the procedure according to the invention. The X-ray system comprises a tube with a focal spot, which are uniformly given the reference number 1, since, as mentioned above, when the procedure according to the invention is carried out and during the subsequent reconstruction of the examination spatial extent 5 (also called ROI = region of interest of the object 2), the imaging characteristics do not depend on the distinction between these two.

[0029] Since the X-ray systems used to perform the procedure according to the invention are known from the prior art, only those components and their function that are relevant to the present invention will be described here.

[0030] From the focal point 1, X-rays 10 are emitted in the form of a fan or cone beam, which impinge on a detector 3 arranged at a fixed distance from the focal point. This fixed distance is called FDD. The detector 3 is impinged perpendicularly by the central ray 11 of the fan or cone beam 10. Whether a fan or cone beam 10 is used depends on whether information is acquired in only one or two dimensions. The detector 3 is adapted to the type of X-rays, i.e. in the case of a fan beam 10, a linear detector is used, in the case of a cone beam 10, a range detector is used.

[0031] The focal point 1 forms the origin of a Cartesian coordinate system, where the x-axis corresponds to the central ray 11 (and thus extends horizontally in FIG. 1), the y-axis extends vertically upwards in FIG. 1, and the z-axis is perpendicular to the plane of the page and points upwards from the page.

[0032] The object 2 to be examined is fixed on a manipulator (not shown), which can translate along the x-axis and rotate about a rotation axis 4 oriented parallel to the z-axis. In the illustrated embodiment example, the object 2 is fixed on the manipulator in such a way that the spatial extent to be examined is arranged around the rotation axis 4 of the manipulator, which does not necessarily have to be translatable parallel to the y-axis. To arrange the spatial extent 5 around a central ray 11 when the individual fluoroscopic images are produced during the entire procedure according to the invention, the rotation axis 4 does not have to be displaced accordingly in the y direction.

[0033] As mentioned above, due to the flat structure of the object 2 (which is many times more extended in the second dimension than in its third dimension), the distance between the focal point 1 and the object 2 on the x-axis (i.e. the spatial extent to be examined) can be varied depending on the rotation angle Θ of the rotation axis 4 (this is the angle between the extent of the object 2 and the x-axis in a plane parallel to the xy-plane). This follows from the fact that no collision with the tube 1 must occur when the object 2 rotates about the rotation axis 4 and that, due to its narrow depth extent, the object 4 can be closer to the focal point 1 in the region of a rotation angle Θ=90° than in the region of a rotation angle Θ=0°. The variable distance between the focal point 1 and the rotation axis of the object 2 is called FOD. The objective of the procedure according to the invention is to make the magnification of the spatial extent 5 (FDD / FOD) as large as possible at each individual rotation angle Θ. In FIG. 1 the resulting change in FOD is shown as an example for six rotation angles from Θ=90° to Θ=0° with constant angle increments of 18°.

[0034] This procedure, referred to in the prior art as a variable magnification CT procedure, in which a constant angular increment is used between the creation of successive fluoroscopic images (see the left part of FIG. 5), is modified by the procedure according to the invention. In order to better understand the concept behind the modification according to the invention, reference is made to FIGS. 2 to 4.

[0035] In these figures, by way of example, voxels 6 (i.e. spatial extent elements) of a spatial extent 5 are represented clearly outside the axis of rotation 4 in order to make the underlying geometrical relationships better visible.

[0036] 2 shows the situation when two successive perspective images of a voxel 6 of the same spatial extent 5 are produced during a rotation around the rotation axis 4 by an angular increment dr°. The rotation angle Θ is in the region of 90°, which corresponds to the representation in the top left image of FIG. 1. The structure of the detector 3 is shown in more detail, as a result of which its detector elements 30 can be recognized. The position of the projection of the voxel 6 in the two positions represented on the detector 3 has hardly changed, in particular the two projections are located in the same detector element 30.

[0037] In contrast to FIG. 2, FIG. 3 illustrates such a situation during the creation of two successive fluoroscopic images around the rotation axis 4 with an angular increment dr° of the same size as in FIG. 2. However, here the rotation angle Θ is in the region of 0°, which corresponds to the representation of the bottom right image in FIG. 1. Due to the equal angular increment dr°, there is a much larger effect on the projection of the voxel 6, even though the absolute change in the rotation angle Θ is identical to FIG. 2. The projections are now not located on the same detector element 30, but on several detector elements 30a, 30b spaced apart from one another.

[0038] In order to achieve a similar sampling in the rotation angle range shown in FIG. 3 as in the rotation angle range shown in FIG. 2, a smaller angle increment dr° must be used in the case shown in FIG. 3 (area around Θ=0). This is shown in FIG. 4. In the case of conventional CT, a part of the spatial extent 5 is located in the area in front of each rotation angle Θ, so that the choice of the angle increment dr° is always adapted to the case according to FIG. 3. Conversely, in the case of a flat object 2, such as for example a printed circuit board (the same is quite generally true for non-circular objects 2), the time and dose for the creation of the projections and thus the creation of the fluoroscopic images can be saved if the object 2 is located in the area of ​​the rotation angle Θ shown in FIG. 2 (i.e. 90°).

[0039] Thus, according to the invention, the angular increment dr° can be selected to be significantly larger in the region of rotation angles Θ between 90° and 270° than in the region of rotation angles Θ between 0° and 180°. This is illustrated in FIG. 5. In the left part, the FOD as a function of the rotation angle Θ of a CT procedure with variable magnification, known from the prior art and already described above for an object 2 (extending many times more in its second dimension than in its third dimension) according to the definition in the context of the present application, is illustrated, whereas in the right part of FIG. 5, the corresponding one is illustrated for the procedure according to the invention for the same object 2. Each point in the image corresponds to the position at which the generation of the fluoroscopic image takes place. It can be easily recognized that, while in the procedure according to the invention, for rotation angles Θ in the region around 0° and 180°, angular increments dr° are used that are approximately equal to the angular increments in the right part, in other angular ranges, in particular for rotation angles Θ in the region of approximately 90° and 270°, the angular increments dr° in the procedure according to the invention are robustly larger than those of the prior art. As a result, significantly fewer fluoroscopic images need to be created to reconstruct the spatial extent 5 of the object. This results firstly in time savings due to the fact that fewer positions need to be generated for fluoroscopic images (as well as the time required for creating them) and also in the risk of damaging the object 2 due to a reduced dose load on the spatial extent 5. On the other hand, the quality of the reconstruction of the spatial extent 5 is hardly compromised compared to procedures known from the prior art.

[0040] In the example embodiment according to the invention shown in FIG. 5 , perspective images were made starting from a rotation angle Θ=0° and at the following angle increments dr° (the unit of measurement ° has been omitted in each case): 0.701000, 0.701000, 0.700000, 0.701000, 0.700000, 0.700000, 0.700000, 0.700000, 0.699000, 0.698000, 0.698000, 0.697000, 0.697000, 0.696000, 0.695000, 0.695000, 0.693000, 0.69300 0,0.692000,0.690000,0.690000,0.688000,0.687000,0.685000,0.685000,0.683000,0.681000,0.680000,0.679000,0.677000,0.675000,0.6730 00,0.672000,0.670000,0.668000,0.666000,0.664000,0.662000,0.660000,0.658000,0.655000,0.654000,0.651000,0.648000,0.647000,0.644 000,0.641000,0.639000,0.636000,0.634000,0.631000,0.628000,0.626000,0.623000,0.620000,0.617000,0.614000,0.611000,0.608000,0.60 5000,0.602000,0.599000,0.596000,0.592000,0.589000,0.586000,0.583000,0.579000,0.576000,0.572000,0.569000,0.566000,0.562000,0.5 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.645000,0.648000,0.650000,0.652000,0.654000,0.657000,0.659000,0.661000,0.663000,0.665000,0.667000,0.669000,0.671000,0.672000,0.675000,0.676000,0 .677000,0.680000,0.680000,0.683000,0.683000,0.685000,0.687000,0.687000,0.689000,0.690000,0.691000,0.692000,0.693000,0.694000,0.695000,0.696000,0 .696000,0.697000,0.698000,0.698000,0.699000,0.699000,0.700000,0.700000,0.701000,0.700000,0.701000;whereas the procedure depicted on the left side of Figure 5 used a constant angle increment of 0.8°.

[0041] It is obvious to the skilled person that the above-mentioned movement of the object 2 and the axis of rotation 4 with a fixed tube 1 and a fixed detector 3 can be achieved with the same result by inverse kinematics. Now, as described in the general description of the invention and as an alternative solution in claims 4-6, the object 2 is fixed and the imaging system consisting of the tube 1 and the detector 3 moves around the object 2 accordingly. The skilled person will be aware that a further detailed description of the corresponding embodiment examples is not necessary, since such designs are known from medical technology in the case of CT systems. However, here a modification is made in that the rotation of the frame, called gantry, is not always performed around the same axis of rotation, but rather around a virtual axis of rotation. This virtual axis of rotation moves correspondingly to the above description and to the claims 4 and 6. [Explanation of symbols]

[0042] 1 (X-ray) tube / focal point 2. Objects 3 (X-ray) detector 4 Rotation Axis 5. Spatial Expansion 6. Voxels 10 X-rays (fan beam or cone beam) 11 Central Radiation 30 Detector element 30a Detector element 30b Detector element 30' detector element 30” detector element Θ Rotation angle dr° Angle increment

Claims

1. 1. A method for generating perspective images for reconstructing the spatial extent (5) of a flat object (2) using an X-ray system, said X-ray system having three imaging components: a tube (1), a detector (3) and a manipulator located between said tube (1) and said detector (3), on which said object (2) is fixed; the object (2) is multiple times larger in a second dimension, called the surface area, than in a third dimension, called the thickness, of the object (2); The tube (1) has a focal point (2) which forms the origin of a Cartesian coordinate system at the center of the tube (1) and emits X-rays (10), the vector passing through the spatial extent 5 from the tube 1 forming the x-axis of the coordinate system and the z-axis perpendicular to the vector formed through the thickness, the manipulator is rotated about a rotation axis (4) that is perpendicular to the x-axis and extends parallel to the z-axis, and is displaceable parallel to the x-axis; said axis of rotation (4) extends through said spatial extent (5) each time a perspective image is generated; When the object (2) rotates around the axis of rotation (4), the distance between the tube (1) and the axis of rotation (4) is changed so that the distance between the object (2) and the tube (1) is as small as possible without falling below the minimum distance definable for each rotation angle (Θ), fluoroscopic images are generated at predefinable rotation angles (Θ), the angular increment (dr°) between adjacent predefinable rotation angles (Θ) being larger when the distance from the tube (1) to the axis of rotation (4) is small than when the distance from the tube (1) to the axis of rotation (4) is large; method.

2. 2. The method of claim 1, wherein the object (2) is fixed on the manipulator before the method starts so that the spatial extent (5) is located on the rotation axis (4) of the manipulator.

3. 2. The method of claim 1, wherein the spatial extent is positioned in angular increments (dr°) such that by manipulator movements along the x- and / or y-axes the resulting effective rotation axes (4) lie within the spatial extent (5).

4. The method described in claim 3, wherein the resulting effective rotation axis (4) is located at the center of the spatial extent (5).

5. 1. A method for generating fluoroscopic images for reconstructing the spatial extent (5) of a flat object (2) using an X-ray system, the X-ray system having three imaging components: a tube (1), a detector (3), and an object holder located between the tube (1) and the detector (3), on which the object (2) is fixed; the object (2) is multiple times larger in a second dimension, called the surface area, than in a third dimension, called the thickness, of the object (2); The tube (1) has a focal point (2) which forms the origin of a Cartesian coordinate system at the center of the tube (1) and emits X-rays (10), the vector passing through the spatial extent 5 from the tube 1 forming the x-axis of the coordinate system and the z-axis perpendicular to the vector formed through the thickness, the position and orientation of the tube (1) and the detector (3) relative to each other are always the same, and the combination of the tube (1) and the detector (3) is called an imaging system; the imaging system is rotated about an axis of rotation that is perpendicular to the x-axis and extends parallel to the z-axis, and is displaceable parallel to the x-axis; said axis of rotation extends through said spatial extent (5) each time a perspective image is generated; When the object (2) rotates around the axis of rotation, the distance between the tube (1) and the axis of rotation is changed so that the distance between the tube (1) of the imaging system is as small as possible without falling below a minimum distance definable for each rotation angle (Θ), fluoroscopic images are made at predefinable angles of rotation (Θ), the angular increment (dr°) between adjacent predefinable angles of rotation (Θ) being larger when the distance from the tube (1) to the axis of rotation is small than when the distance from the tube (1) to the axis of rotation is large; method.

6. 6. The method of claim 5, wherein the tube (1) and the detector (3) are fixed on a frame that is rotatable about an axis oriented parallel to the z-axis and displaceable along the x-axis.

7. 6. The method of claim 5, wherein the spatial extent is determined by moving the imaging system along the x-axis such that the resulting axis of effective rotation is positioned within the spatial extent (5) in angular increments (dr°).

8. The method described in claim 7, wherein the resulting axis of effective rotation is located at the center of the spatial extent (5).

9. 6. The method according to claim 1 or 5, wherein the central ray (11) of the X-ray (10) is located on the x-axis and impinges perpendicularly on the detector (3) at a central position.

10. The method according to claim 1 or 5, wherein the x-axis does not impinge on the center of the detector (3).

11. 6. The method of claim 1 or 5, wherein the ratio between the maximum and minimum angle increment (dr°) corresponds to the ratio between the width of the object and the depth of the object.

12. A method as described in claim 1 or 5, wherein when the object (2) has a substantially rectangular surface area, the ratio between the maximum and minimum angle increments (dr°) corresponds to the ratio between the long and short sides of the object.

13. 6. The method according to claim 1 or 5, wherein the angular increment (dr°) is varied inversely proportional to the distance of the axis of rotation (4) or of the axis of rotation from the tube (1).

14. The method according to claim 1 or 5, wherein the distance between the object (2) and the tube (1) per angular increment (dr°) is between 0.1 and 20 mm.

15. 6. The method according to claim 1 or 5, wherein a predefinable shortest distance between the tube (1) and the axis of rotation (4) or between the tube (1) and the axis of rotation is not less than.

16. 6. The method according to claim 1 or 5, wherein the minimum distance is selected to be at least large enough so that the spatial extent (5) is always fully illuminated.

17. The method of claim 1 or 5, wherein the selection of the minimum distance and / or the shortest distance is established before the rotation begins.

18. The method according to claim 1 or 5, wherein the object (2) is an electronic component.

19. A method as described in claim 1 or 5, wherein the object (2) is a printed circuit board.

Images